JPS6147922B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for manipulating aggregate in an asphalt plant.

In an asphalt plant that produces an asphalt mixture by mixing heated aggregate with stone powder, asphalt, etc., the asphalt mixture is generally produced by the following procedure.

First, cold aggregate made of sand, crushed stone, etc. is stored in a plurality of aggregate hoppers according to particle size, and then predetermined amounts of various types of cold aggregate are taken out from these aggregate hoppers and dried and heated together in a dryer. Subsequently, the dried and heated aggregates are sieved again and stored in silos according to particle size. Then, a predetermined amount of the aggregate stored in the silo is taken out from the silo according to particle size and mixed with stone powder and asphalt in a mixer to produce an asphalt mixture.

However, in the past, cold aggregates stored in aggregate hoppers according to particle size were mixed during the process of drying and heating in a dryer, so the particle size distribution of each aggregate was disrupted when stored in aggregate hoppers. A problem arose. Therefore, the aggregates that have been dried, heated and mixed are sieved by particle size before being stored in the silo, but despite this sieving, the particle size of the aggregate stored in the silo is It is affected by the amount of aggregate fed, changes in the mixing ratio of aggregates, and changes in sieving efficiency.
This variation in the particle size of the aggregate within the silo was a contributing factor to the instability of the quality of the asphalt mixture.

In addition to the above method, there is a method in which only aggregate of a single grain size is taken out from an aggregate hopper, dried and heated, and the aggregates of uniform grain size are sequentially stored in a silo (so-called single grain sinking). However, since sand is generally the most frequently used aggregate in asphalt plants, when using single-grain sinking as described above, there was a problem of waiting for the sand to be weighed. In addition, if the single-grain aggregate used as single-grain crushed stone is crushed stone with a large particle size (for example, No. 4 crushed stone, No. 5 crushed stone, etc.) as described above, equipment wear and noise may occur during the transportation, drying, and heating processes. There were problems with this. Furthermore, if only aggregates with large particle diameters are dried and heated in a dryer, the aggregates roll within the dryer, resulting in a short residence time and a problem that drying is not achieved sufficiently.

This invention was made to solve the above-mentioned problems, and by flowing only two types of materials, sand and crushed stone of a predetermined grain size, it stabilizes the grain size of the aggregate stored in the silo, and In addition to eliminating the need to wait for sand to be weighed, it also reduces equipment wear and noise.
Another object of the present invention is to provide a method for manipulating aggregate in an asphalt plant that allows efficient drying and heating.

The present invention will be explained below based on the drawings.

The drawing shows an embodiment of an asphalt plant to which the present invention is applied. This asphalt plant uses sand _A1 , crushed stone _A2 of different particle sizes,
A ₃ , ... (for example, No. 4, No. 5, No. 6 crushed stone) and other cold aggregates A are stored in a plurality of aggregate hoppers H ₁ , H ₂ , H ₃ , etc. according to particle size, and these A dryer 1 that dries and heats the cold aggregate A taken out from the aggregate hopper H ₁ , a screen 2 that sieves the aggregate dried and heated by this dryer 1 according to particle size, and stores the sieved aggregate according to particle size. The main components are a silo 3, a weighing hopper 4 that weighs the aggregate A taken out from the silo 3, and a mixer 5 that stirs and mixes the aggregate weighed in the weighing hopper 4 with asphalt B to produce an asphalt mixture. It is configured as.

A cold aggregate discharge port 7 is provided at the bottom of each of _{the aggregate hoppers H 1 .} While a conveyor 8a is provided for conveying the cold aggregate A to the chute K,
The chute K is provided with conveyors 8b and 8c for conveying the cold aggregate A to one end 1a of the dryer 1.

The dryer 1 is a cylindrical rotary dryer that is inclined so that one end 1a of the dryer 1 is higher than the other end 1b. A duct D is connected to a secondary dust collector such as a back filter (not shown) through a dryer duct 9 of a gravity sedimentation dust collection type. and the other end 1b of the dryer 1
A burner 10 is attached to the dryer 1, and a discharge chute 11 is attached below the burner 10 for discharging the aggregate dried and heated in the dryer 1.
The outlet 11a of the discharge chute 11 faces the input port 12a of the first elevator 12 through which the aggregate is input into the screen 2.

On the other hand, the screen 2 has a first sieve chamber 14 in which a first vibrating screen 13 such as a wire mesh having a predetermined mesh size is stretched on the bottom, and a mesh smaller than that of the first vibrating screen 13. A second vibrating screen ₁₅ such as a wire mesh that allows the sieves 1 to pass through is installed in communication with a second sieve chamber 16 slanted at the bottom and one end of the first sieve chamber 14 so that the vibrating screen 15 does not pass through the first vibrating screen 13. Oversized chute 17 that discharges large particle size aggregates to the outside of screen 2
, a crushed stone bin 18 for storing crushed stone whose upper end is open at one end of the second sieve chamber 16, a sand bin 19 for storing sand whose upper end opening is covered by the second vibrating screen 15, and the crushed stone bottle 18 and sand bottle 1
9, an outlet 18a formed at the bottom of each of the
cut gates 18b for opening and closing 19a, respectively;
19b, and an aggregate chute 20 provided below the discharge ports 18a, 19a. and the first and second vibrating screens 13,
15, crushed stone of a predetermined particle size is stored in a crushed stone bin 18.
Furthermore, the sand _A1 is sieved into sand bins 19, respectively.

Further, the lower end of the aggregate chute 20 faces the input port 21a of the second elevator 21 through which aggregate is input into the silo 3.

Inside the silo 3, there are a plurality of storage rooms C ₁ ,
C ₂ , C ₃ , and C ₄ are provided, and a funnel-shaped discharge portion 22 is provided at the bottom of each of the storage chambers C ₁ to _{C 4} . Further, a rotary chute 23 is rotatably attached to the upper part of the silo 3, and the opening at the upper end of this rotary chute 23 is used to transport sand _A1 , crushed stone _A2, etc. carried in from the second elevator 21 to the silo 3. The lower end of the rotary chute 23 is positioned below one end of the silo conveyor 24 that conveys the material to the center of the upper part of the storage chambers _C1 to _C4 , and the lower end of the rotary chute 23 is arranged to face any one of the openings _C0 in the ceiling walls of the storage chambers C1 to C4. ing. The rotary chute 23 is connected to the second elevator 21.
It is rotated in accordance with the particle size of the aggregate being conveyed by the , so that the aggregate can be put into predetermined storage chambers C ₁ to C ₄ according to particle size.

25 is a skip device for conveying the asphalt mixture produced by the mixer 5 to the transportation means 6; 26 is a bin leveler for detecting the amount of sand in the sand bin 19; 27 is an asphalt spray; 28 is an asphalt tank; hot oil heater,
30 is a heat insulating material for the silo 3.

Next, a method of operating cold aggregate in the asphalt plant configured as above will be explained.

First, sand A ₁ is taken out from the aggregate hopper H ₁ and crushed stone A ₂ of a predetermined particle size is taken out from the aggregate hopper H ₂ and conveyed together to the dryer 1 by conveyors 8a, 8b, and 8c, where they are dried and heated. At this time, dryer 1
The moving speed of cold aggregate A such as crushed stone A ₂ is such that only crushed stone A ₂ moves inside the dryer 1 because sand A ₂ is sent into the dryer 1 together with the crushed stone A ₂ . slower than sand A ₁ and crushed stone A ₂
is efficiently and sufficiently dried and heated in the dryer 1. Furthermore, since sand A ₁ and crushed stone A ₂ flow through the dryer 1, there is less wear on the dryer 1 and less noise than when only the crushed stones A ₂ are moved within the dryer 1.

Then dry heated sand _A1 and crushed stone as above
Aggregates such as A ₂ are carried into the screen 2 by the first elevator 12 . Then, the first vibrating screen 13 guides crushed stone larger than a predetermined particle size in the aggregate to an oversize chute 17. Then the second
The vibrating screen 15 sieves crushed stones of a predetermined particle size and guides them into the crushed stone bin 18 , and the sand A ₁ passes through the second vibrating screen 15 and flows into the sand bin 19 . At this time, the aggregates carried into screen 2 are sand A ₁ and crushed stone A ₂
Since this aggregate is sieved into two stages by the first and second vibrating screens 13 and 15, the area of the first and second vibrating screens 13 and 15 is reduced to make the screen 2 smaller. can be converted into In addition, the aggregate to be sieved by screen 2 is sand A ₁ and crushed stone A ₂ .
Because of the different types of crushed stone and sand, the sieving accuracy is better compared to sieving aggregates made of many types of crushed stone and sand, and the crushed stone A ₂ and sand A ₁ flowing into the crushed stone bin 18 and sand bin 19 are
The particle size is also stabilized.

On the other hand, in order to transfer crushed stone A ₂ and sand A ₁ stored in the crushed stone bin 18 and sand bin 19 to the silo 3, the rotary chute 23 is rotated and the lower end of the rotary chute 23 is moved to any of the storage chambers C ₁ to C ₄ . Position it at opening _C0 . Then, either the outlet 18a of the crushed stone bin 18 or the outlet 19a of the sand bin 19 is opened, and either crushed stone _A2 or sand _A1 is carried into the silo 3 by the second elevator 21. It flows into any of the storage chambers C ₁ to C ₄ . After this inflow is completed, the rotary chute 23 is rotated again to position the lower end of the rotary chute 23 in an opening _C0 different from the above, and the sand _A1 or the crushed stone _A2 that was not inflowed in the above is removed. One of them is made to flow into any of the storage chambers C ₁ to _{C 4} that were not used above. However, in this case, sand A ₁ , which is used in the largest amount in the asphalt plant, is stored in the storage room with the largest capacity among storage rooms C ₁ to _{C 4} (in this example
_C1 ).

To store crushed stone A ₃ with a different particle size from the crushed stone A ₂ in the silo 3, take out the sand from the aggregate hopper H ₁ and the crushed stone A ₃ from the aggregate hopper H ₃ and repeat the same process as above. The crushed stone A 3 is then heated and dried in the dryer 1 and the crushed stone A ₃ is sieved into the crushed stone bin 18 from which the crushed stone A ₂ has been discharged, and the sand A ₁ is sieved into the sand bin 19 .

Then, similarly to the above, crushed stone A ₃ and sand A ₁ are separately introduced into the storage chambers C ₁ to C ₄ of the silo 3 and stored. At this time, sand A ₁ is stored in a storage room with the same maximum volume as above, and crushed stone A ₃ is stored in a storage room different from the storage room in which the crushed stone A ₂ is stored.

As described above, various crushed stones with different particle sizes are
One of A ₂ , A ₃ ...... and sand A ₁ are dried and heated together in a dryer 1, sieved, and stored separately in a silo 3. As a result, a large amount of sand _A1 is always stored in the silo 3, so that the amount of sand in the silo 3 never runs out. Therefore, there is no need to wait for the weighing of sand, which occurs in the case of conventional so-called single-grain sinking.

Note that the present invention can be implemented in asphalt plants other than those shown in the figure, and the overall structure of the asphalt plant, dryer 1, screen 2, silo 3, etc.
The specific structure of the plant components is arbitrary.

As explained above, in the present invention, cold aggregate is stored in a plurality of aggregate hoppers according to particle size, and sand is taken out from one aggregate hopper and one type of crushed stone is taken out from another aggregate hopper. The sand and crushed stone, which have been dried and heated in a dryer, are transported to a screen where they are separated into sand and crushed stone, and each is stored separately in a silo storage room. Compared to the previous case, there is less wear and tear on the equipment that transports cold aggregate and the dryer, and there is also less noise. Further, by carrying out the above method, the movement of the cold aggregate within the dryer is stabilized, so that the cold aggregate can be sufficiently dried and heated. Furthermore, when many types of cold aggregates with similar particle sizes are dried together in a dryer as in the past, changes in feed rate, mixing ratio, etc. directly affect the sieving accuracy of the screen. The particle size distribution will be significantly different from the particle size distribution when the aggregate hopper is stored, but in this invention, since crushed stone, which is one type of sand, is dried and heated together with the dryer, their Differences in particle size often occur, and even if the feed rate, mixing ratio, etc. change, the sieve can be accurately sieved to its original state regardless of these changes, so the particle size distribution will not be disrupted. Furthermore, by using the above method, a large amount of sand can always be stored in the silo, so there is no need to wait for the weighing of sand, which occurs in conventional single-grain sinks.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of an asphalt plant to which the present invention is applied, and FIG. 3 is a sectional view of a silo of the same embodiment along line A-A. A...cold aggregate, _A1 ...sand, _A2 , _A3 ...crushed stone,
H ₁ , H ₂ , H ₃ ... aggregate hopper, 1 ... dryer,
2...screen, 3...silo.

Claims (1)

[Claims] 1 Store cold aggregate in multiple aggregate hoppers according to particle size, take out sand from one aggregate hopper and one type of crushed stone from another aggregate hopper, dry and heat them together in a dryer, and then dry and heat them together in a dryer. A method for operating aggregates in an asphalt plant, characterized in that the sand and crushed stone that have been dried and heated are transported to a screen to be separated into sand and crushed stone, and each is stored separately in a storage room of a silo.